(a) Technical Field of the Invention
The present invention relates to gear cluster for a bicycle, and in particular, an improved structure of gear cluster which enables rapid gear-shifting and a small force for gear-shifting action.
(b) Description of the Prior Art
Conventional gear cluster for bicycle is mounted at the lower end of the vertical support of the bicycle and is closely located at the position of the crankshaft. In order to avoid interruption with the movement of the crankshaft while pedaling the bicycle, the gear cluster is designed with great limitation. Further the cable for triggering the gear cluster is fixed to the seat frame. When gear shifting, the chain has to be partially at the other corresponding gear plate so as to proceed with gear shift. As a result, the gear cluster design cannot be easily improved.
Taiwanese patent application no. 90205591 relates to an improved structure of a gear cluster. The crank shaft seat is provided with a securing ring mount having gear bust therein which can be moved forward or backward. The external side of the housing is provided with gear plate so that the user can directly control the gear bush so as to change the inner and external teeth mount and the combination with the planetary gear. However, in this conventional gear cluster, it is laborious to adjust.
In view of the above, it is an object of the present invention to provide an improved structure of gear cluster for bicycle which can solve the above-mentioned drawbacks.